In everest the memory was able to read 9800mb/s +- Thats quite good for old x48 chipset. Most setups I have seen were able to read only 7800mb/s. I plan to hit 10gb/s by only tuning the MCH without overclocking.

well. I have Xeon x3360, basically xeon version of Q9550...

Althought the CPU is overclocked, and northbridge is loaded by 4 cores and 4 memory sticks (+graphic card) I really dont see any reason to raise Vnb voltage. Its X48 and 400Mhz FSB is its stock frequency.

I expect it to run fine only with CPU VTT raised a bit. Everything else should run on stock voltages. Except fact that Intel expects 1600Mhz memory to run on 1,9v (therefore at this configuration 1,9v is stock voltage for memory controller integrated in northbridge, but insanely high for memory).

At all the chipset is manufactured by infamous 90nm technology... even on stock with active air cooling its quite hot - 45 degrees of celsius. On 1,34 or more it produces up to 55 and I have seen also 65 when one fan stopped spinning ...